Exhaust flap means

ABSTRACT

An exhaust flap means for motor vehicles comprises an exhaust flap ( 10 ) connected with a flap shaft ( 12 ). In order to pivot the exhaust flap ( 10 ), the flap shaft ( 12 ) is connected with a pivot mechanism. The flap shaft ( 12 ) is supported via at least one bearing means ( 20 ) which comprises a plain bearing sleeve ( 22 ). The flap shaft ( 12 ) is radially supported by the plain bearing sleeve ( 22 ). According to the invention, a contact element ( 28 ) is connected with the flap shaft ( 12 ) to form an axial bearing. The contact element ( 28 ) bears on a face ( 26 ) of the plain bearing sleeve ( 22 ) and thus forms an axial bearing.

The present application claims priority to German Patent Application No. 10 2004 046 076.0, filed Sep. 23, 2004, which application is incorporated herein fully by this reference.

BACKGROUND OF THE INVENTION

The invention relates to an exhaust flap means for motor vehicles.

Particularly in bulky motor vehicle internal combustion engines, it is known to switch off individual cylinders in certain driving situations in order to save fuel. To maintain the required exhaust gas counter pressure in the exhaust gas system, exhaust flaps are arranged in one or more exhaust pipes. The exhaust flaps are connected with a flap shaft supported in at least one bearing means. Via a lever or a linkage, if necessary, a pivoting mechanism for pivoting the exhaust flap is connected to the flap shaft. Thereby, the exhaust flap can be arranged in different positions, particularly an open and a closed position, in the exhaust pipe. Apart from maintaining the exhaust gas counter-pressure in the exhaust gas system, exhaust flaps also serve to simulate the original sound of the engine when cylinders are switched off. The flap shaft may also be supported by a plain bearing sleeve serving as a radial bearing. Additionally, it is required that a separate axial bearing is provided for the axial support, which often is a bearing specifically constructed for this application. Providing a separate axial bearing leads to high mounting requirements. Further, such axial bearings are expensive.

SUMMARY OF THE INVENTION

It is the object of the invention to provide an exhaust flap means with a simple and cost-effective bearing arrangement.

This object is solved, according to the invention, with the features of claim 1.

According to the invention, at least one bearing means for supporting the flap shaft is provided, the bearing means comprising a plain bearing sleeve that is preferably made of graphite or comprises a high amount of graphite. According to the invention, the plain bearing sleeve is arranged or configured such that it does not only serve as a radial bearing but also as an axial bearing. To this end, according to the invention, the flap shaft is connected with a contact element, e.g., a ring extending radially outward. The contact element is contacted by a front face of the plain bearing sleeve for forming the axial bearing. The front face of the plain bearing sleeve, which typically has the form of a circular ring, thus serves as an axial bearing in connection with the contact element connected with the flap shaft. By the implementation of the radial bearing and the axial bearing by means of a single plain bearing sleeve according to the invention, the number of components and thus the mounting requirements are considerably reduced. Further, it is no longer necessary to provide an expensive separate axial bearing so that the costs can be considerably reduced thereby.

According to the invention, at least one bearing means comprises a plain bearing sleeve serving as an axial bearing or as a radial bearing. If necessary, a second bearing means for supporting the flap shaft may be provided. If necessary, it may be a bearing comprising a plain bearing sleeve for the radial support. A second axial bearing arrangement is not required. Further, the second bearing means may also comprise a ball bearing.

The at least one bearing means is preferably arranged in an exhaust flap housing. The exhaust flap housing preferably is a tubular housing. Preferably, the at least one bearing means is provided at an outside of the exhaust flap housing. Likewise, the exhaust flap means may be directly mounted in the exhaust pipe so that the exhaust pipe itself represents the exhaust flap housing.

To ensure a sure contact of the front face of the plain bearing sleeve with the contact element connected with the flap shaft, the contact element, in the direction of the front face, and/or the plain bearing sleeve, in the direction of the contact element, are preferably loaded by an axial force. The axial force is preferably applied by a spring element such as an elastomer, a spring and the like.

It is particularly preferred to provide a spiral spring as a spring element, which surrounds the flap shaft and preferably presses the contact element in the direction of the face of the plain bearing sleeve.

Preferably, the spring element is arranged such that it additionally serves as a restoring element for restoring the pivot mechanism into a normal position of the exhaust flap, e.g., an open position or a closed position. To this end, the spring element is preferably supported on the exhaust flap housing or an intermediate element connected with the exhaust flap housing.

Preferably, the plain bearing sleeve that preferably includes graphite is sealed against an exhaust gas flow. By sealing, it is avoided that the plain bearing sleeve comes into contact with a major amount of oxygen since oxygen in connection with high temperatures would damage the graphite plain bearing sleeve. Preferably, a cap is provided which particularly surrounds a free end of the plain bearing sleeve. Thereby, it is avoided that exhaust gases and thus oxygen flow through the plain bearing sleeve. Preferably, the cap is the contact element. The flap may surround the plain bearing sleeve completely or implement a sealing in combination with a housing element surrounding the plain bearing sleeve.

BRIEF DESCRIPTION OF THE DRAWING

Hereinafter, the invention is explained in detail with respect to a preferred embodiment with reference to the accompanying drawing.

The FIGURE shows, partially in section, a schematic view of a bearing portion of a preferred embodiment of the exhaust flap means according to the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The exhaust flap means comprises an exhaust flap 10 that is firmly connected with a flap shaft 12. A projection 14 of the flap shaft 12 is connected with a non-illustrated pivot mechanism via a lever 16. Via the pivot mechanism, the exhaust flap 10 arranged within a tubular exhaust flap housing 18 can be pivoted. The exhaust flap 10 can be particularly pivoted into a closed position and into an open position in which the exhaust flap 10 is arranged in flow direction.

The flap shaft 12 is supported by a bearing means 20. The bearing means 20 comprises a plain bearing sleeve 22. The plain bearing sleeve 22 initially serves as a radial bearing of the flap shaft 12.

The plain bearing sleeve 22 is arranged in a housing element 24 which is configured as a sleeve as well. The sleeve 24 is configured such that it is a little bit shorter in longitudinal direction than the plain bearing sleeve 22. The plain bearing sleeve 22 is pressed into the sleeve 24 in such a manner that the plain bearing sleeve 22 protrudes with respect to the sleeve 24 at that end which is the upper one in the FIGURE. Thus, a front face 26 of the plain bearing sleeve 22 is freely accessible. At the front face 26, the axial bearing is formed by a pot-shaped contact element 28 bearing on the front face 26 in the illustrated embodiment. The contact element 28 is firmly connected with the flap shaft 12 and the projection 14 of the flap shaft 12, respectively. The front face 26 of the plain bearing sleeve 22 thus bears on an inner surface of the pot-shaped contact element 28. The pot-shaped contact element 28 is axially pressed in the direction of the front face 26 by a helical spring 30. To this end, the helical spring 30 surrounds the flap shaft 12. On the one hand, the helical spring 30 is supported on an annular projection 32 of the pot-shaped contact element and, on the other hand, on a cylindrical housing element 34. The housing element 34 is connected with the exhaust flap housing 18 and further comprises an anti-twist device. The anti-twist device retains one end of the helical spring 30. This results in that the helical spring 30 is twisted when the pivot mechanism is actuated so that the spring 30 simultaneously acts as a restoring element by means of which the exhaust flap 10 is turned back into a normal position, e.g., an open position, when the pivot mechanism is released.

In order to avoid damage to the plain bearing sleeve 22 that preferably comprises graphite, the plain bearing sleeve 22 is sealed. This is effected by the sleeve 24 surrounding the plain bearing sleeve 22 as well as by the pot-shaped contact element partially covering the sleeve 24. This ensures that a small portion of exhaust gases and thus of oxygen at most flows through the plain bearing sleeve 22 and causes damage to the plain bearing sleeve in connection with the high temperature.

Although the invention has been described and illustrated with reference to a specific illustrative embodiment thereof, it is not intended that the invention be limited to this illustrative embodiment. Those skilled in the art will recognize that variations and modifications can be made without departing from the true scope of the invention as defined by the claims that follow. It is therefore intended to include within the invention all such variations and modifications as fall within the scope of the appended claims and equivalents thereof. 

1. An exhaust flap means for motor vehicles, comprising an exhaust flap, a flap shaft connected with the exhaust flap, a pivot mechanism connected with the flap shaft, and at least one bearing means for supporting the flap shaft, the bearing means comprising a plain bearing sleeve, characterized in that the flap shaft is connected with a contact element bearing on a front face of the plain bearing sleeve for forming an axial bearing.
 2. The exhaust flap means according to claim 1, wherein the contact element is loaded by an axial force in the direction of the front face and/or the plain bearing sleeve is loaded by an axial force in the direction of the contact element.
 3. The exhaust flap means according to claim 2, wherein a spring element is provided for applying the axial force.
 4. The exhaust flap means according to claim 3, wherein the spring element is a helical spring surrounding the flap shaft.
 5. The exhaust flap means according to claim 3, wherein the spring element additionally serves as a restoring element for restoring the pivot mechanism into a normal position.
 6. The exhaust flap means according to claim 1, wherein the plain bearing sleeve is arranged in a housing element preferably configured as a sleeve, the front face of the plain bearing sleeve being arranged outside the housing element.
 7. The exhaust flap means according to claim 1, wherein the plain bearing sleeve comprises graphite.
 8. The exhaust flap means according to claim 1, wherein the plain bearing sleeve is sealed with respect to an exhaust gas flow. 